Axial flow compressors for jet engines



Aug. 9, 1966 A. J. CALI 3,265,290

AXIAL FLOW COMPRESSORS FOR JET ENGINES Filed Sept. 1, 1964 2 Sheets-Sheet 1 F G. I INVENTOR.

ANTHONY J: CALI M J aw A TI'ORIVEX 9, 1966 A. J. CALI 3,265,290

AXIAL FLOW COMPRESSORS FOR JET ENGINES Filed Sept. 1, 1964 2. Sheets-Sheet 2 um \\i\\ INVEN TOR. ANTI/0N) .z CALI BY M J-M ATTORNEY 3,265,290 AXIAL FLOW COMPRESSURS FOR JET ENGINES Anthony 5. Cali, 2030 Bath Ave., Brooklyn, NRY. Filed Sept. 1, 1%4, Ser- No. 393,608 Claims. (Cl. 230-122) This invention relates to axial flow compressors for jet engines.

Axial flow compressors for jet engines usually include a plurality of compressing stages wherein the air is caused to flow through a series of successive compressing rotor sections of decreasing diameter in a direction from the front or inlet end to the rear or outlet end of the compressor. The rotor sections are longitudinally spaced from each other along the longitudinal axis of the compressor and an intervening stationary stator section is provided between adjacent pairs of rotor sections. Each of the stator sections is provided with guide vanes and the stator sections also decrease in diameter in a direction from the front to the rear end of the compressor. A fairing is provided at the rear end of the compressor for guiding the compressed air from the compressor to the next section of the engine and the fairing has a diameter which is smaller than the diameter of the last rotor section.

To assemble the rotor and stator sections alternately with respect to each other, a stator section is placed over a rotor section and, thereafter another rotor section is placed in position, and the next stator section is placed endwise against the previous stator section and is loosely interconnected therewith. This repetitive assembly procedure of rotor, stator, rotor, etc. continues until all the stator sections are loosely interconnected to each other with the compressing blades of the intervening rotor sections between the guide vanes of the stator sections. The adjacent ends of adjacent stator sections are provided with intermeshing lugs and slots whereby the ends of the stator sections are removably supported on each other. The fairing is similarly supported on the rear or last stator section and is placed on said last stator section after the last rotor section is placed in position since the last rotor section has a diameter which is greater than that of the fairing.

During operation of the compressor, it has been found that because of vibrations and other forces, especially at the rear or outlet end of the compressor where the pressures are high, the rear stator section and fairing vibrate excessively causing excessive wear on the stator section lugs as well as on the edges of the slots of the fairing, as well as causing other detrimental effects. In certain cases, the front edge portion of the fairing had buckled such that repair was not practicable and replacement was necessary. The excessive wear between the fairing and adjacent stator section was extremely dangerous and required very expensive maintenance to correct such wear before it reached dangerous proportions.

I have discovered that not only can such wear be minimized, but it can be eliminated entirely and without any time consuming or expensive redesign or reconstruction of the compressor.

The primary object of the present invention is to provide a compressor of the above indicated type wherein the wear between the fairing and stator section is eliminated.

A further object is to provide an improved method of assembling the rotor and stator sections and fairing of an axial flow compressor.

Another object is generally to provide an improved compressor of the indicated type whose maintenance costs are considerably less than those compressors which do not incorporate the present invention.

The above and other objects, features and advantages of the invention will be more fully understood from the following description of the invention considered in connection with the accompanying drawings of a presently preferred illustrative embodiment of the invention in which:

FIG. 1 is a longitudinal cross section of a compressor in accordance with the invention, the compressor being positioned vertically;

FIG. 2 is a longitudinal cross section of the outlet end of the compressor and illustrates, in dot-dash lines, the method of assembling the last rotor section of the compressor;

FIG. 3 is a detail cross sectional view through a portion of the adjacent edges of the fairing and adjacent stator section;

FIG. 4 is a sectional view taken on line 44 of FIG. 3, but on a larger scale; and

FIG. 5 is an external view of a portion of the adjacent edges of the fairing and adjacent stator section.

Referring now to the drawings in detail and first with reference to FIG. 1, the axial flow compressor 10 comprises an inlet section 12 which includes an outer circular ring or shroud 14 and an inner concentric circular ring 16 connected to the shroud by a series of circumferentially spaced, radially extending, inlet stationary guide vanes 18. A hearing support 20 is suitably connected to inner ring 16 and a bearing support cover 22 is suitably secured to support 20, as by a circular ring of bolts 24. The main forward bearing for supporting the forward end of the rotor 26 is indicated at 28.

Rotor 26 comprises a series of longitudinally aligned rotor sections 30a, 30b, 30c, 30d, 30c, 30 30g and 30h which are spaced from each other longitudinally of the longitudinal axis of the compressor and the diameter of each successive rotor section decreases in a direction from the front or inlet end of the compressor to the rear or outlet end of the compressor. Rotor section 30a is provided with a hub 32 which projects forwardly into bearing support 20 and the inner race of bearing 28 is fixed to the hub while the outer race of the bearing is fixed to the bearing support. The rear part of the hub of rotor section 30a is provided with a circular ring of holes through which a circular ring of front tierods 34 etxends for supporting the other front rotor sections 30b, 30c and 30d in longitudinal spaced relation along the longitudinal axis of the compressor. Proper spaced relation between the rotor sections is assured by the provision of disk spacers 36. A conical disk spacer 38 is provided between rotor sections 30d and 30c and another circular ring of rear tie-rods 34a secures the rear rotor sections 30a, 30 30g and 30h in longitudinal spaced relation with respect to each other along the longitudinal axis of the compressor. A cone-like member 40 is secured to rotor section 30h and the rear section of member 40 (not shown) is supported in a rear bearing (not shown) for supporting the rear or outlet end of the compressor. Each rotor section has a series of circumferentially spaced rotary compressor blades 42a, 42b, 42c, 42a, 42e, 421, 42g and 42h which extend radially outwardly from the hub or central portion of the respective rotor section. As indicated previously, the diameters of the compressor blades decrease in a direction from the inlet end to the outlet end of the compressor.

The stator 44 of the compressor comprises a series of longitudinally aligned stationary stator sections 46a, 46b, 46c, 46d, 445e, 46 and 46g which are arranged in endto-end relation along the longitudinal axis of the compressor and decrease in diameter in a direction from the inlet end of the compressor toward its outlet end. Each stator section comprises a circular shroud or body por- Patented August 1966 tion 48 from which extends radially inwardly, toward the longitudinal axis of the compressor, along the rear portion of the shroud, a series of circumferentially spaced stationary guide vanes 50 which terminate at a circular inner ring 52 to which they are secured. It is to be noted that the vanes are positioned in the rear portion of its respective shroud which extends forwardly to provide a space in which the blades of the adjacent rotor section are positioned. Thus it is seen that guide vanes 50a, 50b, 50c, 50d, 50s, 50 and 50g are each positioned between pairs of successive rotor blades. The shroud is frustoconical in shape with its forward end being of larger diameter than its rear end. Reference will now be made to all figures of the drawings.

With the exception of the forward marginal edge portion of front stator section 46a, the forward marginal edge portion of each stator section comprises a circular rim 52 provided with a series of circumferentially spaced slots 54. The rear marginal edge portion of each of the stator sections comprises a rim 56 from which longitudinally extends circumferentially spaced lugs 58 which extend into the companion slots 54 so that the lugs of the rear end of one stator section intermeshes with the slots of the forward end of the adjacent stator section for loosely interconnecting the stator sections to each other in end-to-end relation. As best seen in FIG. 4, the bottom edge portion of the forward end of each stator section is provided with an abutting edge 60 and an abutting shoulder edge 62 forwardly and outwardly of edge 60. The forward edge 64 of rim 52 abuts against edge 62 and the forward edge 66 of the stator section abuts against edge 60. The shrouds are provided with outer longitudinally spaced circular stiffening ribs 68.

The forward marginal edge portion of stator section 46a is loosely interconnected with the rear marginal end portion of shroud 14 of the inlet section in a similar, though not ncessarily an identical manner as the adjacent ends of the stator sections. The outlet end of the compressor has a fairing 70 whose forward marginal edge portion is identical to the forward marginal edge portion of the stator sections, except section 46a, to permit interconnecting the fairing to the outlet stator section 46g as hereinafter described in accordance with the invention. The fairing 70 comprises a circular body portion 72 whose annular side wall resembles a pair of end-to-end frusto-conical sections. More particularly, and as best seen in FIG. 2, the side wall first extends rearwardly from the rear end of the outlet stator section 46g, and concomitantly radially inwardly toward the longitudinal axis of the compressor to a position 74 wherein the diameter of the side wall is less than that of the adjacent rotor 30/1 and, thereafter, the side wall continues rearwardly but concomitantly extends radially outwardly from the longitudinal axis of the compressor.

In assembling the stator and rotor sections, as referred to previously, stator section 46a is placed over rotor section 30a. Next, rotor section 30b is placed in position over stator section 46a and the next stator section 4611 is placed over rotor section 30b, and this alternate manner of assembling the rotor and stator sections is continued. No difiiculty is encountered in assembling the fairing 70 to stator section 46g since rotor section 30h, whose diameter is greater than portion 74 of the fairing, is assembled prior to the mounting of the fairing. The compressor is provided with an outer case 75.

The loose interconnections between the stator sections permit ready disassembling of the sections for maintenance. However, as indicated previously, the high pressures at the outlet end of the compressor have caused considerable vibration and other detrimental effects which cause excessive wear between the interconnected ends of stator section 46g and fairing 70, and in certain cases have caused the fairing to buckle. According to the invention, this may be eliminated by fixedly joining the fairing 70 and stator section 416g to each other and in a manner which does not interfere with the assembly of the stator section, fairing and rotor section 3011. More particularly, a series of circumferentially spaced welds 76 is provided across the outer surface of rim 52 of the fairing and the outer surface of rim 56 0f the stator section between lugs 58. Since the fairing and stator section are joined to each other, rotor section 30h must now be assembled in the compressor after the fairing- The larger diameter rotor section can be so assembled in the manner illustrated in dot-dash lines in FIG. 2 by tilting the rotor section and placing one side thereof below position 74 of the fairing and in the larger diameter inlet end of the fairing, against its side wall. Since the wall of the inlet end of the fairing is of relatively thin material and since the relative dimensions of the restricted portion 74 and the diameter of the rotor section 42h are relatively close, albeit the rotor section is of greater diameter, the rotor section, when tilted, will exert some pressure against the inner wall of the fairing and due to'the thin nature of the material and the relative resilience thereof, the same will flex somewhat outwardly thereby allowing the rotor section to snap into position past the restricted portion or venturi 74. This permits the opposite side of the rotor section to clear the adjacent side Wall of the fairing at position 74 whereby the larger rotor section can be passed through the smaller fairing for assembly to the rear tierods 34a.

While I have shown and described the preferred embodiment of the invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in the form and arrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying ideas or principles of this invention within the scope of the appended claims, and in this regard it will be understood that it is within the scope of the invention to make fairing 70 and stator section 46g in one piece.

What is claimed is:

r1. An axial flow compressor for a jet engine comprising a series of longitudinally aligned stationary stator sections arranged in end-to-end relation along the longitudinal axis of the compressor, each of said sections comprising a circular shroud having an inlet end and an outlet end and a front marginal circumferentially extending edge portion at said inlet end and a rear marginal circumferentially extending edge portion at said outlet end, said inlet end having a diameter greater than said outlet end, a series of circumferentially spaced guide vanes positioned in the rear portion of said shroud and extending radially inwardly toward said longitudinal axis, said front edge of said shroud being positioned forwardly of said guide vanes, the rear edge portion and front edge portion of adjacent stator sections having loosely interengaging parts for loosely interconnecting said stator sections to each other, a fairing having a front edge rigidly connected to the rear edge portion of an adjacent stator section and having a circular body portion extending rearwardly and radially inwardly from said fairing front edge to a particular diameter and, thereafter, reawardly and radially outwardly to a larger diameter, a series of longitudinally aligned rotor sections spaced from each other longitudinally along the longitudinal axis of said compressor, each rotor section being positioned between successive pairs of stator sections in the space between the front edge of the stator section and its guide vanes, and a rotor section positioned within said fairing body portion between said fairing front edge and said position of said fairing body portion at said particular diameter and adjacent said guide vanes of said adjacent stator section, said last mentioned rotor section having a diameter which is greater than said particular diameter.

2. An axial flow compressor as defined in claim 1, wherein said interengaging parts of said adjacent stator sections comprises a series of circumferentially spaced lugs on one of said stator sections interengaging corresponding circumferentially spaced slots on the other of said stator sections.

3. An axial flow compressor'as defined in claim 1, wherein said front edge of said faring and said rear edge portion of said adjacent stator section are provided with interengaging parts comprising a series of circumferentially spaced lugs intermeshed with a series of circumferentialy spaced slots, and means between said lugs and slots rigidly connecting said fairing and adjacent stator section to each other.

4. An axial flow compressor as defined in claim 1, wherein said interengaging parts of said adjacent stator sections comprises a series of circumferentialy spaced lugs on one of said stator sections interengaging corresponding circumferentially spaced slots on the other of said stator sections, and wherein said front edge of said fairing and said rear edge portion of said adjacent stator section are provided with interengaging parts comprising a series of ci-rcumferentialy spaced lugs intermeshed with a series of circumferentially spaced slots, and means between said lugs and slots rigidly connecting said fairing and adjacent stator section to each other.

5. A combined stator section and fairing for an axial flow compressor for a jet engine comprising, a stationary stator section having an annular shroud provided with an inlet end and an outlet end and a series of stationary circumferentially spaced guide vanes at said outlet end extending radially inwardly from said shroud toward the longitudinal axis of said shroud, said shroud having a cireumferentially extending marginal edge portion along said outlet end, and a fairing comprising a circular annular wall having an inlet end and a circnmferentially extending marginal edge portion along said inlet end secured to said marginal edge portion of said shroud, said annular wall extending from its inlet end longitudinally, continuously, smoothly and unobstructedly away from said shroud and converging radially inwardly toward the longitudinal axis of said annular wall and axially away from said shroud and, thereafter diverging smoothly, continuously, and unobstructedly, radially outwardly away from said last mentioned longitudinal axis.

References Cited by the Examiner UNITED STATES PATENTS 2,702,665 2/1955 Ledwith 230133 2,722,373 11/1955 Ledwith et al 230-133 2,912,823 11/1959 Lawson 60-3931 2,936,978 5/1960 Lauck 6039.31 3,004,700 10/1961 Warren 230133 MARK NEWMAN, Primary Examiner.

HENRY F, RADUAZO, Examiner. 

1. AN AXIAL FLOW COMPRESSOR FOR A JET ENGINE COMPRISING A SERIES OF LONGITUDINALLY ALIGNED STATIONARY STATOR SECTIONS ARRANGED IN END-TO-END RELATION ALONG THE LONGITUDINAL AXIS OF THE COMPRESSOR, EACH OF SAID SECTIONS COMPRISING A CIRCULAR SHROUD HAVING AN INLET END AND AN OUTLET END AND A FRONT MARGINAL CIRCUMFERENTIALLY EXTENDING EDGE PORTION AT SAID INLET END AND A REAR MARGINAL CIRCUMFERENTIALLY EXTENDING EDGE PORTION AT SAID OUTLET END, SAID INLET END HAVING A DIAMETER GREATER THAN SAID OUTLET END, A SERIES OF CIRCUMFERENTIALLY SPACED GUIDE VANES POSITIONED IN THE REAR PORTION OF SAID SHROUD AND EXTENDING RADIALLY INWARDLY TOWARD SAID LONGITUDINAL AXIS, SAID FRONT EDGE OF SAID SHROUD BEING POSITIONED FORWARDLY OF SAID GUIDE VANES, THE REAR EDGE PORTION AND FRONT EDGE PORTION OF ADJACENT STATOR SECTIONS HAVING LOOSELY INTERENGAGING PARTS FOR LOOSELY INTERCONNECTING SAID STATOR SECTIONS TO EACH OTHER, A FAIRING HAVING A FRONT EDGE RIGIDLY CONNECTED TO THE REAR EDGE PORTION OF AN ADJACENT STATOR SECTION AND HAVING A CIRCULAR BODY PORTION EXTENDING REARWARDLY AND RADIALLY INWARDLY FROM SAID FAIRING FRONT EDGE TO A PARTICULAR DIAMETER AND, THEREAFTER, REAWARDLY AND RADIALLY OUTWARDLY TO A LARGER DIAMETER, A SERIES OF LONGITUDINALLY ALIGNED ROTOR SECTIONS SPACED FROM EACH OTHER LONGITUDINALLY ALONG THE LONGITUDINAL AXIS OF SAID COMPRESSOR, EACH ROTOR SECTION BEING POSITIONED BETWEEN SUCCESSIVE PAIRS OF STATOR SECTIONS IN THE SPACE BETWEEN THE FRONT EDGE OF THE STATOR SECTION AND ITS GUIDE VANES, AND A ROTOR SECTION POSITIONED WITHIN SAID FAIRING BODY PORTION BETWEEN SAID FAIRING FRONT EDGE AND SAID POSITION OF SAID FAIRING BODY PORTION AT SAID PARTICULAR DIAMETER AND ADJACENT SAID GUIDE VANES OF SAID ADJACENT STATOR SECTION, SAID LAST MENTIONED ROTOR SECTION HAVING A DIAMETER WHICH IS GREATER THAN SAID PARTICULAR DIAMETER. 